A gas turbine is provided with a compressor for generating compressed air by compressing air, a combustor for generating a combustion gas by burning a fuel in the compressed air, and a turbine driven by the combustion gas. The compressor has a compressor rotor that rotates around an axial line and a compressor casing covering the compressor rotor. The turbine has a turbine rotor that rotates around the axial line and a turbine casing covering the turbine rotor. Both the compressor rotor and the turbine rotor have a rotor shaft and a plurality of blade rows attached to an outer circumference of the rotor shaft. A gas turbine rotor is formed by placing the compressor rotor and the turbine rotor on the same axial line and connecting them together. Furthermore, a gas turbine casing is formed by connecting the compressor casing and the turbine casing together.
Of the gas turbine rotor, the turbine rotor is exposed to high-temperature combustion gas, and therefore the rotor must be cooled using air, and the like.
A technology for cooling a turbine rotor using compressed air from a compressor is disclosed in Patent Document 1. With this technology, compressed air extracted from a middle stage of the compressor is guided into a compressor rotor of the gas turbine rotor, which compressed air is then guided from the compressor rotor to a turbine rotor to cool said turbine rotor.